Variation in the Food Reserves of Trees. 241 



starch in the winter. However, Petersen found the roots of 

 Bctula verrucosa losing the starch in all their tissues in December, 

 while the roots of Acer pseudoplatanus lost at the same time the 

 starch from the phloem. 



The nine trees reported in this paper were examined at weekly 

 intervals from October to June for the amount of starch in the 

 roots. The phloem of the root of Carya glabra showed some re- 

 duction of starch in December, but the roots of the 8 other trees 

 retained their starch in both phloem and xylem undiminished 

 throughout the winter as far as the microscopical method could 

 determine. All of the species showed a reduction, but not a com- 

 plete loss of starch in their roots in April or May. 



The material taken for examination in winter was not allowed 

 in warm temperature before examination. 



Conceiving the possibility that the retention of starch by the 

 roots in winter might be, at least in part, due to the protection af- 

 forded by their buried condition, roots of the 3 species, Tilia 

 americana, Uhnus americana, and Quercus rubra, were uncovered 

 in midwinter, and exposed to the air, while still connected with the 

 trees. Although these roots were frequently exposed to tem- 

 peratures of — 10° to — 20°, and for 6 weeks almost continuously 

 to a temperature below 0°, there was no perceptible effect on the 

 content of starch. The exposed roots and the unexposed roots 

 presented the same appearance under the microscope. 



Sugar Reserves. 



Since the analytical chemical work of Sablon, sugar can hardly 

 be given the place of importance assigned to it by Fischer, namely, 

 as a large reserve in trees. The examination of the 9 species 

 of trees included in this report demonstrated the presence of a 

 large amount of sugar in the spring only, at the time of the un- 

 folding of the buds. There was an increase of sugar in the late 

 autumn in all species ; but only Juniperus virginiana and Salix 

 alba showed much sugar in any part of the tree at any time except 

 in April and May. The roots of all 9 species showed only traces 

 of sugar at any of the examinations except in April and May. 



Fat Reserves. 



The variations in the amount of fat reported by most of 

 the investigators have been found to hold true for 8 of the 9 



